This invention relates to a tire valve for inflating a tire wheel assembly and for preventing over-inflation and subsequent bursting of the tire during inflation or in road use. Normally tires are inflated up to a safe operating pressure; however, the inflating equipment may have the capacity to overinflate the tire with an inflating medium at an excessively high pressure. This creates a hazard for personnel in the area of the tire during inflation if the tire should burst at that time. The valve of this invention is also useful to release excessive tire pressure which might be developed in service.
Prior to the present invention, safety relief valves have been devised in which pressure release devices were incorporated in the valve stem; however, their design has been expensive to manufacture and difficult to adjust and service. Accordingly, it has not been practical to provide valves of this design on the number of installations where this safety feature is desirable. With the safety valve designs proposed heretofore, the valve stems have had an increased length to accommodate the additional mechanism and this has made the valves more vulnerable to damage. There has also been a problem in servicing and adjusting the pressure release mechanism because it was incorporated in the same valve stem as the inflation valve core. In addition, there was no visible indication that the pressure release mechanism had been actuated and accordingly the tire may have been put into use in an underinflated condition. There was also the problem of releasing the inflating medium from the tire at a rate exceeding the inflation rate to effectively prevent overinflation.